Posted
by
timothy
on Thursday April 09, 2009 @04:11PM
from the for-all-your-sticking-to-stuff-needs dept.

AndreV writes "Biomimetic adhesives aren'tnew, but a PhD graduate in British Columbia has developed a new method of creating microscopic, mushroom-like plastic structures in order to produce a dry adhesive that mimics the stickiness of gecko feet—and is prepping his glue-free innovation for outer space. A research group at his university, in collaboration with the European Space Agency, is engineering a spider-like, sticky-footed climbing robot destined to explore Mars, and it is also developing reusable attaching systems for astronauts to use where magnetic and suction systems generally fail. In the future, he says, single-use versions could be used in any number of medical applications as well as for replacements for everyday sticky needs, such as Post-It notes and Scotch tape."

A friend of mine studied this stuff for his Ph.D research. It's the molecular-level adhesive force between the Gecko's feet and the surface that allows it to cling. That force is relatively-weak but when multiplied by a few million "pads" on the foot, it's strong enough to let a lizard climb up a wall. Or a robot.

First synthetic gecko adhesive which cleans itself during use, as the natural gecko does. After contamination by microspheres, the microfiber array loses all adhesion strength. After repeated contacts with clean glass, the microspheres are shed, and the fibers recover 30% of

If you RTFA you will see that this new adhesive is not based on the nano-scale properties of gecko feet, but is the first space adhesive that doubles as a delightful gecko-flavored paste in emergencies.

You know, I hate it when my fingers feel sticky, even if they really aren't "sticky" in that stuff that I pick up stays stuck. You touch the backside of a post-it, and then for a little while they are sticky afterward. Or you touch scotch tape, and same thing - the fingers are just tacky and it feels weird in a fingers-down-the-blackboard sort of way.

There is no way I'd want to be in Space and have to touch this stuff, and then not be able to get it off by washing my hands. I prefer to get my fingers sticky

Someone needs to collect all the scientific knowledge expressed in slashdot posts, and write a text book. Why hide this useful archive of scientific truths in obscure blog posts when we can use it to illuminate the minds of the children?

My 8 year old asked why you can't divide by 0. Said her teacher told her that she shouldn't do that but now she wants to know why she shouldn't do it. Sigh. I showed her divide by zero error on a calculator./damn my art school (won't need math for this degree!) drop out education (even art school has homework requirements)

Ah, this is perfect. Totally makes sense, compared to that far off high school algebra class, back in the early '80's. I mean, you'd think a football coach who'd played for the Browns would also be a decent math teacher, wouldn't ya!

Yeah, because they still ignore that the result (infinity) is i two-component result (much like complex numbers), but with the second component being (i guess) temporal.That way, you do not lose anything, and can still use formulas with infinity inside them, and get useful results too.

In my eyes, zero and infinity (there are two types: the negative and the positive one, just like with zero) are in the same group.You could also see zero as some kind of infinity. Because you can go smaller and smaller, and ne

If you can divide by zero, numbers make no sense. That's amazing you say, has somebody ever tried to divide by zero and did bad things happen as a result?

Yes, do you remember the banking crisis of 2008, that's when 1 tiny bank accidentally divided by zero. Through the internet this ofcourse rapidly spread and soon numbers made no sense. Because they made no sense, the virtual money indicator flipped to negative. That's why your house has lost 50% of its value.

Actually, that isn't neccesairy. Landing at an inconsistency with assumed premisses and a correct system, disproves the premisses. The second you land at 2=3 is the second that you know that dividing by zero is nonsense.

Think of it this way, though: in calculus, you can calculate limits, some of which go to infinity. Therefore, infinity is a useful concept. Take the limit as n approaches zero from the positive side:

lim n -> +0 (3/n - 2/n)

The limit goes to infinity. However, if you try to compute the value at n = 0, both terms are infinite - and subtracting them gives positive infinity, which indicates that they aren't the same (or it would equal zero).

Except that isn't accurate. 1/0 != infinity. Does infinity * 0 = 1? No... of course not. Since multiplication is the inverse function of division... your statement is incorrect. Now if you'd written lim(x->0) of [1/x] is infinity, you'd have been right.

x/0 for any non-zero number is simply undefined. Its not useful for tran

...and that's why they say "infinity is not a number". A value can be infinite, but it doesn't actually equal infinity, because no such number exists.

Well, I'm not sure who you are identifying as saying that infinity is not a number, but unfortunately they are not correct. You're statement that two infinite values may not be equal certainly has validity to it. Transfinite mathematics and hyperreals deal with rigorous analysis of s

In mathematics, "infinity" is often used in contexts where it is treated as if it were a number (i.e., it counts or measures things: "an infinite number of terms") but it is a different type of "number" from the real numbers.

http://en.wikipedia.org/wiki/Infinity [wikipedia.org]
In mathematics, "infinity" is often used in contexts where it is treated as if it were a number (i.e., it counts or measures things: "an infinite number of terms") but it is a different type of "number" from the real numbers.

I never said it was a real number. Although whether it is or not kind of depends on what kind of mathematics you are doing.

Note in this context the phrase "real numbers" is referring to the set of Reals, as opposed to say the set of Imaginari

It said "treated as if it were a number". It put "number" in quotes. Both of those indicate that it's not really a number, and the use of "real number" is a regrettable choice of words in attempting to express that.

Look, I'm not really contradicting you. Infinity is sometimes treated as if it were a number - it's sometimes convenient and useful to do so. However, that doesn't make it a number. So you're one of the people who's used to treating it as if it were a number - naturally you'll take exception when someone says it isn't.

Look, I'm not really contradicting you. Infinity is sometimes treated as if it were a number - it's sometimes convenient and useful to do so. However, that doesn't make it a number. So you're one of the people who's used to treating it as if it were a number - naturally you'll take exception when someone says it isn't.

Infinity is a number, full stop. What makes something a number? What is a number? A count of something? A quantity of something? That concept that expresses the count or quantity of some

"The count" doesn't exist if it is infinite. It's uncountable. It doesn't equal infinity; it's infinite. There's a subtle difference.

I'm afraid you are digging yourself deeper here. I actually made a mistake in my previous post asking for a count of Real Numbers since the Reals are not countable... However, infinite sets in general are not uncountable. The other example, for counts that I gave, the integers are certainly a countable set. Rationals are another infinite and countable set. Wikipedia is yo

Ok, I didn't realise "countable" could include a discrete infinite series. I was under the impression that it could only be used to refer to a finite set, part (1) from its definition in the Wiki...

A set is countable if: (1) it is finite, or (2) it has the same cardinality (size) as the set of natural numbers.

Anyway, moving on...

what is 3?... the collection of sets that contain 3 elements.

That's not a number, that's a concept. "3" is a number. "Sets having 3 elements" is a concept - a rule which enables us to categorise something as "fits" or "doesn't fit". Thus, 3 can be thought of as either a number or a concept.

You explained to her she shouldn't do something because a machine can't do it either?

I'd use the good-old-pie-fractions example. Take a pie. Divide it into two parts, explain that's dividing by two. Cut it again, so it's four parts. Explain you divided it by four. Cut twice more and ask how many pieces there are (that's how many you divided by).Now, give her the knife, and ask her to divide it into zero parts. Explain that's why she can't divide by zero... no matter how many times you cut, no matter how you approach it, you cannot end up with zero parts.

Actually, I dropped out of art school in '93. Turned out that, while I had no great design skills, I was great at fixing Macs in the computer lab. And at the print shops where student were always bringing in effed up layouts with missing font files. Next thing I knew, people were calling me, offering booze and money to get the shiny out of the machine or show them out to make Photoshop or Illustrator do what they wanted. Now, still with no degree, I'm a senior Macintosh analyst at a national lab that my cra

If there are 6 apples, and everyone gets two, how many people can share the apples? Three people. What if they can only have one apple? Then six people can share the apples.

What if nobody can have any of the apples? Then nobody can share the apples, but the apples don't get eaten. That's why you can't divide by zero: the apples never get used up. In fact, you could have a hundred people, or a thousand, or as many as you want, and every one of them won't get an apple... and there will still be six apples.

The problem with "zero divided by zero equals zero" is that it is equally true that "zero divided by zero equals twelve". How many zeros does it take to equal zero? Zero, one, two, pi, anything. It's undefined.
And here ends my first slashdot post where I am literally arguing over nothing.

The problem with "zero divided by zero equals zero" is that it is equally true that "zero divided by zero equals twelve".

Good point. So the correct answer to "zero divided by zero" would be {R}, the set of real numbers... or possibly the set that includes both real and imaginary numbers; not sure how they behave in regular arithmetic.

No, it would depend on the derivative of the expression that gave 0 at that particular point. If you evaluate 2/x at 0, you get division by zero. If you evaluate x/(x - 2) at x = 2, you get division by zero also.

However, in one case the limit would give 0/1, or 0, whereas the second limit would give 1/1, or 1.

Well, according to http://en.wikipedia.org/wiki/Gecko [wikipedia.org] dust and dirt that could prevent the van der Waals forces that geckos toes use, are removed within a couple steps due to "self-cleaning" properties. If they are able to reproduce the effect properly, the lifespan of the product could be quite significant.

For those that need a monetary reason to save the environment, this is a poster child. We can learn a huge amount of useful things from studying nature. If that nature is allowed to die out, then we will miss out on the hidden knowledge.

Ever since some years ago we read on/. that they had discovered the secret behind geckos' amazing abilities, I've been waiting for practical applications of this in the form of gecko tape and the soon-to-follow gecko shoes and gloves.

Glad to see that they'll be using it in space soon, guess that means it'll only be a matter of time before I can get it at Home Depot. In the meantime, whenever I want something stuck to the wall, I just tie it to a gecko and then let the gecko do the sticking for me. Tough part is keeping them in one place, but ironically a little traditional glue does the job nicely. The other problem is I can only put things out of the reach of my cat...

Tough part is keeping them in one place, but ironically a little traditional glue does the job nicely.

In which case, you're using glue anyway.

I find it's much simpler to use a staple gun to affix the geckos to the wall.

I use the staples made for insulated wire, otherwise the staples go right through 'em and all you have to show for it is a perforated gecko twitching on the floor... which is the same result as within-reach-of-the-kitty gluing.

Ever since some years ago we read on/. that they had discovered the secret behind geckos' amazing abilities, I've been waiting for practical applications of this in the form of gecko tape and the soon-to-follow gecko shoes and gloves.

...

Not to detract too much from your post... but Ive been using gecko tape and gloves for a few years now though probably not as advanced as the stuff in TFA:

Greptile [3m.com] is 3m's name for it. I use handlebar tape made with it on my road bike, and before it went out of production (Seems to be only used for golf equipment and Nascar steering wheels these days), had the gloves to match. With the gloves on the tape it was like a weak velcro. Even with normal gloves it has more grip than normal tape.

First synthetic gecko adhesive which cleans itself during use, as the natural gecko does. After contamination by microspheres, the microfiber array loses all adhesion strength. After repeated contacts with clean glass, the microspheres are shed, and the fibers recover 30% of their original adhesion. The fibers have a non-adhesive default state, which encourages particle removal during contact.Contact Self-Cleaning of Synthetic Gecko Adhesive, Langmuir 2008

First synthetic gecko adhesive which cleans itself during use, as the natural gecko does. After contamination by microspheres, the microfiber array loses all adhesion strength. After repeated contacts with clean glass, the microspheres are shed, and